1. Field of the Invention
This invention relates to the cleaning of foreign material from a moving surface and, more particularly, to the removal of excess toner from the fixing rolls of a copy machine.
2. Description of the Prior Art
A variety of situations exist in which the maintenance of a desired surface condition on a moving object is obtained by the utilization of a so-called "doctor blade," in which a leading free edge of the blade abuts against the moving surface to displace any undesired foreign matter. It is often found that notwithstanding the clearing effect of the doctor blade on the moving surface, the matter removed from the surface tends to accumulate at the point where the doctor blade meets the moving surface and the accumulated matter often drops to an undesired portion of the machinery involved.
This is particularly true of copy machines in which a light image of an original to be copied is typically recorded in the form of a latent electrostatic image upon a photosensitive member with subsequent rendering of the latent image visible by the application of electroscopic marking particles, commonly referred to as toner. The visual image can be either affixed directly upon the photosensitive member or transferred to a support member, which may be a sheet of plain paper, with subsequent affixing of the image thereto.
In order to permanently affix or fuse electroscopic toner material onto a support member, pressure must be applied to the toner particles which may or may not be accompanied by heating.
One approach to applying such pressure has been to pass the support member with the toner images between a pair of opposed fuser rolls, one of which may be internally heated. However, toner particles may be offset to the fuser roll by an insufficient application of heat to the surface, if the roll is to be heated; by imperfections in the surface of the roll; or by the toner particles insufficiently adhering to the support member by the electrostatic forces which normally hold them in place. In such a case, toner particles may be transferred to the surface of the fuser roll with subsequent transfer to a backup roll during periods when no copy paper is moving through the rolls. Moreover, toner particles may be picked up by the fuser and/or backup roll from the surroundings of the copying machine.
A doctor blade in contact with the fuser roll has proven effective in removing toner particles. However, there remains the problem of removing accumulated toner from the junction of the doctor blade and the fuser roll.
U.S. Pat. No. 4,218,131 issued to Ito et al. on Aug. 19, 1980, utilizes a screw-type auger to convey accumulated toner particles to a container where they may be reused. The drawback of this system is that a large amount of toner must accumulate at the junction of the doctor blade and the roll before such toner contacts the auger and is conveyed away.
It is desirable to provide a system which will continuously remove excess toner from the junction of the doctor blade and the fuser roll before the toner can accumulate and possibly drop to a portion of the machine where it might cause damage.